Sealing device for a tray sealer

ABSTRACT

A sealing device for sealing trays, the sealing device having a sealing-tool lower part and a sealing-tool upper part. The sealing-tool lower part includes a tray holder. The sealing-tool upper part includes a sealing plate and a cutting knife The tray holder includes a cutting channel into which the cutting knife can dip or, in other words, that may receive the cutting knife, when cutting a film lid for the tray from the film web, the film lid being sealed on the tray.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to German Application Number102012012481.3 filed Jun. 22, 2012, to Jurgen Prasenz and Jochen Makeentitled “Sealing Device for a Tray Sealer,” currently pending, theentire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a sealing device for a tray sealer to sealtrays containing products with a film web, such as food articles, aswell as to a method of operating such a sealing device.

BACKGROUND OF THE INVENTION

DE 10 2005 035 476 A1 discloses a sealing device in which a film web isclamped on a sealing-tool upper part by a clamping plate. A cuttingknife arranged in the sealing-tool upper part carries out a cuttingmovement such that the cutting knife dips into an opening provided inthe clamping plate and cuts a piece of film out of the film web beforethe film is attached to a tray edge and sealed, by use of a sealingplate. In this known inside-cut process, the film is cut prior to beingsealed such that the dimensions of the cut film correspond to the sealedarea so that the film does not extend up to the outermost edge of atray, and no film or only a very small part of the film projects beyondthe sealed seam after sealing. This technique forms a package havingpleasing and neat appearance. Since the film web extends between thesealing-tool upper part and the clamping plate and is pinchedtherebetween, the clamping plate is resiliently guided in thesealing-tool upper part. This embodiment makes it difficult to thread ina new film web after a change of films, and is in some cases obstructiveinsofar as the residual film grid of the film web may get stuck duringfilm transport. In addition, if process irregularities occur, such as aproduct projecting beyond the tray edge of a tray, and the sealingdevice presses the product against the clamping plate, then the clampingplate may be easily damaged.

Other sealing devices are known in the art, such as those described inDE 10 2006 061 309 A1, DE 102 37 933 A1, or DE 10 2008 057 609 A1.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an improved sealingdevice of a tray sealer and a method of operating such a sealing device,which avoid the above shortcomings in the art.

The sealing device according to the present invention comprises asealing-tool lower part and a sealing-tool upper part, the sealing-toollower part including a tray holder and the sealing-tool upper partincluding a sealing plate and a cutting knife The sealing device mayinclude the tray holder having a cutting channel integrated therein andthe cutting knife can dip or be inserted into the cutting channel forcutting a film web. This cutting channel may be defined in that the trayholder includes a reception area as a support for an edge of a tray tobe sealed and in that said reception area may be offset by at least fivemillimeters (5 mm) in a direction away from the sealing-tool upper partrelative to a support surface (or bearing surface) on which the film webof the top film can rest outside of the tray. Thus, a cutting channelmay be formed, which does not merely extend as an annular track aroundthe tray, but into which the tray can be immersed as a whole. Thisprovides the enormous advantage that a clamping plate, which haspreviously been resiliently attached to the sealing-tool upper part bymeans of guide units, may no longer be required in a sealing device. Thepresent sealing device can be implemented with a simpler structuraldesign and enhanced process reliability, and the film web need no longerbe threaded in, but can simply be passed between the sealing-tool upperpart and the sealing-tool lower part in the open condition of the tool.

According to one embodiment, the cutting channel is substantiallyarranged concentrically with or may be congruent with the reception areaof the tray holder so that a package having an aesthetic appearance canbe produced.

Another embodiment includes parallel to a direction of movement of thecutting knife, a distance of three-tenths of one millimeter (0.3 mm) tothree millimeters (3 mm) may be provided between the cutting knife andthe edge of the cutting channel so as to guarantee a high film cuttingquality.

The cutting channel may be arranged above the reception area for an edgeof the tray to be held so as to prevent the cutting knife from cominginto contact with the tray.

The dimension of the cutting channel corresponds at least to theexternal dimension of a tray.

Preferably, the tray holder includes a plurality of cutting channels sothat a multiple split-up tool (i.e. a tool for simultaneously processinga plurality of trays) can be provided for accomplishing a high packagingperformance.

In further embodiments of the present sealing device may include theoffset of the reception area relative to the support surface being atleast six millimeters (6 mm), and preferably six millimeters (6 mm) toten millimeters (10 mm), in a direction away from the sealing-tool upperpart. Tests have shown that an offset in the range of eight millimeters(8 mm) to nine millimeters (9 mm), in particular eight and one-halfmillimeters (8.5 mm), may be particularly advantageous.

A method according to the present invention for operating theabove-described sealing device may include cutting of the film web usingthe cutting knife dipped or inserted into the cutting channel of thetray holder; therefore, this method does not require the use of aclamping plate.

The film web may be pinched or compressed between the sealing-tool upperpart and the tray holder before it is cut, so as to support the cuttingprocess and allow evacuation of the chamber defined by the sealing-toolupper part and the sealing-tool lower part.

Preferably, the cutting knife remains above a sealing plane when thefilm web is cut in the cutting channel, but other configurations may beused.

According to another embodiment, the cut film may be taken hold of bythe sealing plate, when the latter moves towards the tray holder, andpinched or compressed onto the tray, so as to seal the film onto thetray in the sealing plane for allowing film dimensions that project onlya small distance beyond the sealed seam. This configuration may providethe benefit of producing a package having an aesthetic appearance.

Other and further objects of the invention, together with the featuresof novelty appurtenant thereto, will appear in the course of thefollowing description.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, which form a part of the specification andare to be read in conjunction therewith in which like reference numeralsare used to indicate like or similar parts in the various views:

FIG. 1 is a side view of a sealing device of a tray sealer in accordancewith one embodiment of the present invention at an open position;

FIG. 2 is a side view of the sealing device of the tray sealer of FIG. 1at a closed position;

FIG. 3 is a side view of the sealing device of the tray sealer of FIG. 1at a position for cutting a film from a film web;

FIG. 3 a is a blown up detailed side view of the cutting channel of thesealing device of the tray sealer of FIG. 1;

FIG. 4 is a side view of the sealing device of the tray sealer of FIG. 1during the process of sealing the film onto a tray; and

FIG. 5 is a side view of a tray after being sealed by the sealing deviceof the tray sealer of

FIG. 1.

Identical components are provided with identical reference numeralsthroughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawingfigures, in which like reference numerals refer to like partsthroughout. For purposes of clarity in illustrating the characteristicsof the present invention, proportional relationships of the elementshave not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specificembodiments in which the invention can be practiced. The embodiments areintended to describe aspects of the invention in sufficient detail toenable those skilled in the art to practice the invention. Otherembodiments can be utilized and changes can be made without departingfrom the scope of the present invention. The present invention isdefined by the appended claims and the description is, therefore, not tobe taken in a limiting sense and shall not limit the scope ofequivalents to which such claims are entitled.

FIG. 1 shows a side view as a section through a sealing device 1according to the present invention at an open position. A sealing-toolupper part 3 is arranged above a film/foil web 2. In the interior of thesealing-tool upper part 3 a cutting knife 4 and a sealing plate 5 areprovided, which are each independently movable in a vertical directionrelative to one another and to the sealing-tool upper part 3.

A sealing-tool lower part 6 including a tray holder 7 is arranged belowthe film web 2.

The tray holder 7 is provided for accommodating two trays 8, the trays 8being placed with their tray edge 9 (best shown in FIG. 5) onto areception area 10 of the tray holder 7 by means of a gripper system,which is not shown. The reception area 10 is provided with a siliconegasket 11 so as to support the process of sealing the film web 2 to thetray 8. The sealing-tool upper part 3 includes on the lower surfacethereof a silicone gasket 12, wherein silicone gasket 12 supports thepinching or compression of the film web 2 between the sealing-tool upperpart 3 and the sealing-tool lower part 6 and seals the sealing-toolupper part 3 and the sealing-tool lower part 6 relative to one anotherto define an evacuatable chamber.

The tray holder 7 includes a cutting channel 13 above each receptionarea 10. This cutting channel 13 is defined in that the reception area10, which is able to carry the tray edge 9, exhibits an offset V of atleast five millimeters (5 mm), preferably between six millimeters (6 mm)and ten millimeters (10 mm), relative to a support surface (or bearingsurface) 13 a of the tray holder 7. The support surface 13 a is definedin that the film web 2, i.e. the top film 2, rests thereon, when thesealing device 1 is closed. This explanation shows clearly that thecutting channel 13 according to the present invention is, contrary tothe prior art, not a groove that externally surrounds the tray 8, butthe cutting channel is here a recess in the tray holder 7 into which thetray is lowered until it rests on the reception area 10. The offset Vguarantees that, even when a tray 8 has been placed into the tray holder7, a sufficient amount of space is left above this tray for defining anevacuation gap having a dimension of one millimeter (1 mm) to twomillimeters (2 mm), and that, in addition, the cutting knives 4, whichnormally have serrated cutting edges, will also be able to cut adownwardly yielding film web 2 without any risk of penetrating into thematerial of the tray 8 and damaging the tray 8. With an offset of atleast five millimeters (5 mm) a very high process reliability can beaccomplished, even if and in particular if the materials of the tray 8and/or the film web 2 used are comparatively thick and cannot be handledeasily.

While in use, the sealing device 1 is operable to seal one or more trays8 in the following manner At the outset of each operating cycle, thesealing device 1 is open and trays 8 filled with the product in questionare placed into the tray holder 7. The film web 2 is transported farenough in the direction of production P of the tray sealer for itsresidual film grid 14 to be located outside the sealing device 1 or atleast outside the areas of the cutting knives 4.

Subsequently, the sealing device 1 is closed, as shown in FIG. 2. In thecourse of this process, the sealing-tool lower part 6 is lifted andpinches in its upper position the film web 2 together with thesealing-tool upper part 3. The space between the tray 8 and the film web2 can now be evacuated and/or an exchange of atmosphere can be executedby means of gas flushing.

FIG. 3 shows the subsequent method step, during which the cutting knives4 move downwards and dip into (inserted into) the respective cuttingchannel 13 of the tray holder 7 and, in so doing, cut a respective filmlid 15 out of the film web 2, the film lids 15 being intended to be usedas lids for the trays 8. The cutting knives 4 are laterally spaced 21from the edge of the cutting channel 13 and dip into (inserted into) thecutting channel 13 only down to the level of the upper edge 16 of thetrays 8. The cut-out film lids 15 are now located inside the cuttingknives 4 at a small distance 17 from the tray edge 9 onto which they areto be sealed.

Subsequently, the sealing plate 5 is moved downwards, as shown in FIG.4, and, in so doing, it carries along the cut-out film lids 15. At itslower position, which corresponds to its operating position, the heatedsealing plate 5 presses the cut-out film lids 15 onto the tray edge 9and the cut film 15 is sealed onto the tray 8 along a circumferentiallyextending sealing seam 19 (best seen in FIG. 5). The sealing itselfdepends on the temperature of the sealing plate 5, the pressure whichthe sealing plate 5 applies to the trays, and the time for which thesealing plate 5 is at the operating position. Subsequent to the sealingprocess, the sealing plate 5 and cutting knives 4 move upwards relativeto the sealing-tool upper part 3, and the sealing-tool lower part 6moves downwards carrying along the sealed trays 8 and, in so doing,opens the sealing device 1, as shown in FIG. 1.

The constructions and methods described above and illustrated in thedrawings are presented by way of example only and are not intended tolimit the concepts and principles of the present invention. Thus, therehas been shown and described several embodiments of a novel invention.As is evident from the foregoing description, certain aspects of thepresent invention are not limited by the particular details of theexamples illustrated herein, and it is therefore contemplated that othermodifications and applications, or equivalents thereof, will occur tothose skilled in the art. The terms “having” and “including” and similarterms as used in the foregoing specification are used in the sense of“optional” or “may include” and not as “required”. Many changes,modifications, variations and other uses and applications of the presentconstruction will, however, become apparent to those skilled in the artafter considering the specification and the accompanying drawings. Allsuch changes, modifications, variations and other uses and applicationswhich do not depart from the spirit and scope of the invention aredeemed to be covered by the invention which is limited only by theclaims which follow.

What is claimed is:
 1. A sealing device for a tray sealer for sealing atray with a film lid made from a film web, the sealing devicecomprising: a sealing-tool lower part and a sealing-tool upper part, thesealing-tool lower part including a tray holder, the sealing-tool upperpart including a sealing plate and a cutting knife, wherein the trayholder includes a support surface for the film web and a reception areaas a support for an edge of a tray to be sealed, the reception areabeing offset relative to the support surface by at least fivemillimeters (5 mm) in a direction away from the sealing-tool upper part,so that the tray holder has integrated therein a cutting channel intowhich the cutting knife can be inserted for cutting a film web.
 2. Thesealing device according to claim 1, wherein the cutting channel issubstantially arranged concentrically with the reception area of thetray holder.
 3. The sealing device according to claim 1, wherein thecutting channel is substantially congruent with the reception area ofthe tray holder.
 4. The sealing device according to claim 1, wherein alateral distance of around three-tenths-of-one millimeter (0.3 mm) tothree millimeters (3 mm) is provided between the cutting knife and anedge of the cutting channel.
 5. The sealing device according to claim 1,wherein the cutting channel is arranged above the reception area for anedge of a tray to be held.
 6. The sealing device according to claim 1,wherein a dimension of the cutting channel corresponds to an externaldimension of a tray.
 7. The sealing device according to claim 1, whereinthe tray holder includes a plurality of cutting channels.
 8. The sealingdevice according to claim 1, wherein the offset of the reception arearelative to the support surface is at least six millimeters (6 mm) in adirection away from the sealing-tool upper part.
 9. The sealing deviceaccording to claim 1, wherein the offset of the reception area relativeto the support surface is between around seven millimeters (7 mm) toaround ten millimeters (10 mm) in a direction away from the sealing-toolupper part.
 10. A method of sealing a tray in a sealing devicecomprising: inserting a cutting knife into a cutting channel of a trayholder of a sealing device; cutting a film lid out of a film web withthe cutting knife; and sealing the film lid onto a tray after cuttingthe film lid.
 11. The method according to claim 10 further comprisingclamping the film web between a sealing-tool upper part of the sealingdevice and a support surface of the tray holder of the sealing deviceprior to cutting the film web.
 12. The method according to claim 10further comprising maintaining the cutting knife above a sealing planewhile cutting the film lid from the film web.
 13. The method accordingto claim 10 further comprising moving a sealing plate of the sealingdevice towards the tray holder, holding the cut film lid with thesealing plate, and compressing the cut film lid onto a tray in the trayholder to seal the cut film lid onto the tray wherein said cut film lidis located in a sealing plane.